dailysudoku.com Forum Index dailysudoku.com
Discussion of Daily Sudoku puzzles
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Puzzle 11/08/21: ~ XY

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj
View previous topic :: View next topic  
Author Message
daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Sun Aug 21, 2011 6:32 pm    Post subject: Puzzle 11/08/21: ~ XY Reply with quote

Code:
 +-----------------------+
 | . . 4 | 5 . 6 | . 9 8 |
 | . . 2 | 4 . . | . . 7 |
 | 6 7 5 | . . . | . . 4 |
 |-------+-------+-------|
 | 9 5 . | 6 8 . | . . 3 |
 | . . . | 7 3 . | . . . |
 | 7 . . | . . 9 | . . . |
 |-------+-------+-------|
 | . . . | . . . | 9 . 2 |
 | 3 . . | . . . | . 4 . |
 | 5 2 9 | 3 . . | 8 . . |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Mon Aug 22, 2011 4:40 am    Post subject: Reply with quote

XY-Chain. 6 in r9c5 proves 4 in r4c6; r6c5<>4
Skyscraper; r6c9, r8c7<>1
W-Wing (56), SL 5 in r8; r56c7<>6
Back to top
View user's profile Send private message
tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Mon Aug 22, 2011 1:50 pm    Post subject: Reply with quote

I finally found some time for Sudoku. Very Happy

Two solutions; a one stepper and a two stepper.

aur(29)r38c45 external sis: r3c6=2, r8c6=2; r4c6<>2

or

axy-wing(24-1)[r49c6+r6c4]=(7)r9c6-r9c8=r8c7-(7=4)r4c7-(4=2)r4c6-(2=1)r6c4; r5c6,r78c4<>1
Type 1 UR(29)r38c45; r8c5<>29=6

Ted
Back to top
View user's profile Send private message
daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Mon Aug 22, 2011 5:45 pm    Post subject: Reply with quote

Aaaagh!!! I really need to add external SIS logic to my UR() routine.

Nice find, Ted.
Back to top
View user's profile Send private message
ronk



Joined: 07 May 2006
Posts: 398

PostPosted: Mon Aug 22, 2011 9:32 pm    Post subject: Reply with quote

daj95376 wrote:
I really need to add external SIS logic to my UR() routine.

Nice find, Ted.

tlanglet, I second the nice find.

daj95376, Ted's AUR would be destroyed by a co-existent "UR+3C/2SL" for r8c4<>2.

here Mike Barker wrote:
Code:
--- UR+3C/2SL: both strong links share a node, do not include the bivalue cell and have equal labels => "b" can be removed from "abZ"

 ab     abX
         |
        a|
     a   |
abY-----abZ

How would you avoid that in your solver?
Back to top
View user's profile Send private message
daj95376



Joined: 23 Aug 2008
Posts: 3854

PostPosted: Tue Aug 23, 2011 3:37 am    Post subject: Reply with quote

ronk wrote:
daj95376, Ted's AUR would be destroyed by a co-existent "UR+3C/2SL" for r8c4<>2.

Code:
Mike Barker--- UR+3C/2SL: both strong links share a node, do not include the bivalue cell and have equal labels => "b" can be removed from "abZ"

 ab     abX
         |
        a|
     a   |
abY-----abZ

How would you avoid that in your solver?

That UR elimination is one of two found by my solver.

Code:
 +--------------------------------------------------------------+
 |  1     3     4     |  5     7     6     |  2     9     8     |
 |  8     9     2     |  4     1     3     |  56    56    7     |
 |  6     7     5     |  289   29    28    |  3     1     4     |
 |--------------------+--------------------+--------------------|
 |  9     5     1     |  6     8     24    |  47    27    3     |
 |  2     468   68    |  7     3     145   |  1456  568   9     |
 |  7     468   3     |  12    245   9     |  1456  2568  156   |
 |--------------------+--------------------+--------------------|
 |  4     168   678   |  18    56    1578  |  9     3     2     |
 |  3     168   678   |  1289  269   1278  |  1567  4     156   |
 |  5     2     9     |  3     46    147   |  8     67    16    |
 +--------------------------------------------------------------+
 # 63 eliminations remain

 r38c45  <29> UR via s-link              <> 2    r8c4
 r25c78  <56> UR via s-link + N_Singles  <> 6    r5c7
 <s list-only>

Code:
 after r8c4<>2 from strong links UR logic
 +--------------------------------------------------------------+
 |  1     3     4     |  5     7     6     |  2     9     8     |
 |  8     9     2     |  4     1     3     |  56    56    7     |
 |  6     7     5     |  289   29    28    |  3     1     4     |
 |--------------------+--------------------+--------------------|
 |  9     5     1     |  6     8     24    |  47    27    3     |
 |  2     468   68    |  7     3     145   |  1456  568   9     |
 |  7     468   3     |  12    245   9     |  1456  2568  156   |
 |--------------------+--------------------+--------------------|
 |  4     168   678   |  18    56    1578  |  9     3     2     |
 |  3     168   678   |  189   269   1278  |  1567  4     156   |
 |  5     2     9     |  3     46    147   |  8     67    16    |
 +--------------------------------------------------------------+
 # 62 eliminations remain

However, that wouldn't prohibit my solver from continuing with the potential <29> UR.

Awhile back, I re-wrote all of my UR routines to rely on finding an X-pattern in two digits (under UR conditions). The potential UR condition would still be detected because this pattern of candidates still remain.

Code:
 X-pattern in {2,9}
 +-----------------------------------+
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  2  9  .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  .  |  9  2  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 +-----------------------------------+

In fact, thats how my solver detects a UR Type 1.1 elimination where three of the cells are solved and an elimination exists in the fourth cell.

Code:
 UR Type 1.1  =>  r3c5<>b
 +-----------------------------------+
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  a  bX .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |-----------+-----------+-----------|
 |  .  .  .  |  b  a  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 |  .  .  .  |  .  .  .  |  .  .  .  |
 +-----------------------------------+


Regards, Danny
Back to top
View user's profile Send private message
Ertekaz



Joined: 28 Aug 2013
Posts: 1

PostPosted: Wed Aug 28, 2013 3:59 am    Post subject: Reply with quote

Never understand Yet
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group